More than a dozen fires broke out over the weekend, scorching wide swathes of the southeast and forcing around 37,000 people to flee, with the fire cutting off roads and downing communications lines as residents escaped in panic.

South Korea's Ministry of Interior and Safety said that 27 people had been killed and dozens more injured, with the toll likely to rise. It is the highest number of deaths since the Korea Forest Service started records for wildfires in 1987.

More than 35,000 hectares (86,500 acres) of forest have been burned, Lee Han-kyung, disaster and safety division chief said, adding that the fire was still spreading "rapidly".

The extent of damage makes it South Korea's largest ever wildfire, after an inferno in April 2000 that scorched 23,913 hectares across the east coast.

Authorities said changing wind patterns and dry weather had revealed the limitations of conventional firefighting methods.

Many of those killed were residents—in particular the elderly.

At least three firefighters were killed, and a pilot in a firefighting helicopter died when his aircraft crashed in a mountain area, officials said.

'Climate crisis'

Last year was South Korea's hottest year on record, although temperatures in the months running up to the blaze had been colder than last year, and in line with the country's 30-year average, Korea Meteorological Administration data shows.